Means for controlling synchronous machines.



J. BURKE.

MEANS FOR CONTROLLING SYNGHBONOUS MACHINES.

APPLICATION FILED SEPT. 20, 1907;

1,073,662. Patented Sept. 23, 1913.

- 2 sums-3111231 1.

MIDI/(770A! MOTOR /0 POLE .6

'SYIVCHRO/VOUS MACH/NE l2 POLE INDUCTION /Z 2 sr/vcmo/vaus mam/v5 Q/vvhw soeo M 8140014150; 4. $51 hfltkozmmy J. BURKE. MEANS FOR GONTRDLLINGSYNGHBONOUS MACHINES.

APPLICATION FILED 8139120, 1907.

1,073,662; I Patented Sept. 23, 1913.

2 SHEBTSSHEET 2 M npentoz witnesses W i UNITED STATES PATENT OFFICE;

JAMES Bimini, ornmn, rnnns rnyenrs, sssrenon so BURKE npncrnrc coarser,

' A concession or rnnnsynvnme. I

HEARS non oourBoLLms snrcnnouous MACHINES.

Specification of Letters Patent.

Patented Sept. 23, 1913,

p cati fil d cp cm i fi 9 ial N 393,765-

lb all whom it may concern;

Be it known that 1, JAMES BURKE, a cit1- zen of the United States, inthe county of Erie and State of Pennsylvania, have inventedccrtain newand useful Improvements in Means for Controlling Synchronous Machines,of which the following is a full, deaf, and exact specification.

My invention relates to alternating current apparatus and particularlyto a method and means for controlling synchronous machines and thestarting of such machines.

economical starting. The throwing of syn One object lot-my invention isthe securing of efficient means for starting a symchronous motorandbringing the latter into synchronous speed, with a View particularlyto secure safe and reliable operation and chronous apparatus intosynchronous .0pera tion has beena matter of great difliculty, and notonl has required a reliable operating engineer but even then thedisastrous results from an improper 0 ration with resulting damage tothe mac ines, has not been overcome, and with operators who are notreliable and who have not been well trained in the theplacingintosynchronism of large machines is so important that withformer meth ds such operators cannot be given the responsibility.

A further object of my invention relates to the maintaining of themachine in synchronism after being started and thus secure greaterreliability in normal operation.

My invention will be understood from the following description andaccompanying drawings, in which' Figure'l is a diagram showing oneembodiment of my invention, and Fig. 2 is a diagram showing theelectrical connecticmsv of the apparatus of Fig. l,- and Figs. .3, .4and 5 are'dingrams illustrating additional invention.

The source of electric is indicated at 1, and in this particularinstance indi;

- et d a a t o-p se mtb pp y g a twosphas'e system. The synchronous ma.-hine whi is to b ar e and c n r d, is indicated M2, and thismay be amotor P o ing me ha al w r or ay "b in the form .of a rotary converter.Qn the shaft of t synchronous machine; ind cated an exci e! 3 forsupplying current to in fie d wind ng t residing at Erie,

particular mode of operation,

he yn r n u r.

and synchronous machineto proper amounts. Although the exciter is Shownas a shunt wound machine, it will be understood that. a series or acompound Wound machine may be used and the excitation may sometimes beobtained in other ways. and without necessarily mounting the exoiter onthe main shaft. Also on the shaft of the synchronous motor is indicatedan induction motor .6, but it will be understood that this motor may bemechanically connected to the synchronous machine in any other desirablemanner, and a motor other than an induction motor may sometimes be used.For purpose of explanation, I have assumed that the synchronous machinewill have twelve poles and the induction mot r ten pol s.- A main switch.7 is shown between the supply mains and the apparat s to be operatedand aswitch 8 is provided for short circuiting the windings of the motor6 if desired' In Fig. 2, the two-phase windings 9, 10, of the inductionmotor are diagrammatically indicated, and the tWOr'PhaSI-P, windings 11,12,- of the synchronous motor, are similarly indicated. By following theconnections, it will be seen that one winding 9 of the induction motoris connected in series with the corresponding Winding 11 of the synchrornous motor between two of the supply mains of one phase. Also theremaining winding 10 of the induction motor is connected in series withthe corresponding winding 12 of the synchronous motor between theremaining two supply mains.

When it is desired to start the synchronous motor, it is merelynecessary to complete the circuits to the induction motor andsynchronous motor, such as by closing switch 7 or by completing thecircuits with any ot er i ab e f rm of t llin c r dev c l sync motor bne at rest and of course out of synchronism, will'not produce anyappreciable efi'ectiye eo ute e ectr mo ve fi r e, and the Win o he indction mo or will. h -ch e subjec d to a comparat ely h gh epe i e ecromot e force- 11 l e the dugtlon motor to which in will end, that 1s,

' mensurable with the line voltage.-

below that however by the amount of itsslip. When in conjunction withthe synchronous machine, which in this illustration has 12 poles andtherefore at cycles a synchronous speed of 10 revolutions per sec- 600revolutions per minute, at the instant the induction motor attains 10revolutions per second, the synchronous machine comes into synchronismwith the circuit and the counter-electromotive force of the synchronousmotor assumes a value com- This results in thev electromotive force onthe induction motor dropping to a small and unimportant value, the linevoltage now being required to overcome the counter electromotive forceof the synchronous motor, the field excitation of the synchronous motorhaving been built up with the gradual increase in speed. If thesynchronous machine should momentarily drop in speed, such as by reasonof the sudden application of load or from any other cause, the inductionmotor will then become active and exert a strong torque tending to bringthe machine into proper operation. Consequently, the induction'motor notonly serves to start and bring the synchronous motor intosynchronism,but also serves during circuiting the windings of theinduction motor if desired after synchronism is attained.

. is required in starting the to the induction motorwindings an At thistime, as above explained, no appreciable. electromotive force will beapipliid t e latter may therefore be short circuited without harmfuleffects. No energy will then be consumed by the windings an the rotatingelement of the induction motor will then rotate idly.

It will beseen that by-my invention no particular skill '511' the partapparatus, nor 1s it necessary to have any auxiliary devices forindicating to the operator when certain steps are to be taken. It issimply necessary normal operation to oppose any tendency of thesynchronous ma- After at-' terminal of of the operator to close thecircuits originally and the machines then cooperate to increase in speedand attain synchronous speed 'automatically. It will also be seen thatmy invent-ion secures absolute reliability and avoids damage to theapparatus or installation which might result in other cases by impropermanipulation of the apparatus by the operator, and other advantages willbe understood by those skilled in the art.

Although I have indicated a two-phase system in Figs. 1 and 2, it willbe understood that any suitable number of phases may be employed andconnected in various ways. In Fig. 3, I have indicated my inventionembodied in a three-phase system, a three-phase source of electricalenergy being indicated at 13. The three-phase windings of thesynchronous motor are shown at 14 connected in star, and the three-phaseWindings of the induction motor are indicated at 15, 16 and 17. Amainswitch is shown at 18,-and the switch 19 is adapted to short circuitthe induction motor windings dur: ing normaloperation if desired. Itwill be seen that a connection from one of the three-. phase supplymains extends to the winding 15 and thence to a terminal of one ofthestar connected windings of the synchronous machine. Another connectionextends from the intermediate supply main to the winding .16, and thenceto a terminal of a second star connected winding of the synchronousmachine. Another connection extends from the remaining supply mainthrough induction motor winding 17, and thence to its correspondingwinding of the synchronous machine. During starting, the three-phasewindings of the induction motor are therefore connected in series withcorresponding three-phase windings of the synchronous machine, and theaction in starting will be the same substantially as described withreference to Figs. 1 and 2, it being understood that the field of thesynchronous machine will be energized as already described. Aftersynchronous speed is attained, switch 19 I, may be closed and therebyshort circuit the induction motor windings,

In Fig.- 4, the parts similarly numbered correspond to those of Fig. 3,but the windings are differently connected. In Fig. 4, the upper supplymain is connected to a one of the windings 14 and thenceto a terminal ofwinding 15 of the induction motor, which latter winding is connected instar with the remaining induction motor windings 16, 17 Connection fromthe intermediate supply main extends to another winding 14 and thence toa terminal of corresponding winding 16 of the induction motor.Connection from the remainingsupply main extends to the remainingwindlng 14 and thence to a terminal of winding 17. It'will be seen thatin Fig. 3,

' windings of the induction motor.

the current fromthe supply mains in starting will pass first throughthe-induction motor wlndi'ngs to the star connected windings of thesynchronousmachine, whereas in Fig. 4, the current from the supply mainsfirst passes through the windings of thesynchronous machine and then tothe star connected For normal operation, the switch 20 in Fig. 4, may beclosed thereby'shortcircuiting the induction motor windings andresulting in a star connection of the synchronous motor windings.

Although, in the preceding figures, the windings of the induction motorand syn: chronous motor are shown connected directly to the supplymains, it will sometimes be advisable to introduce transformers betweenthe supply mains and either the synchronous motor or the inductionmotoro-r between both, and for the purpose of explanation I have shownin Fig. 5, transformer windings introduced between the supply mains andinduction motor windings. This condition will probably arise in practicemore frequently than others, as, for economy in normal operation, thesynchronous motor will be wound to withstand high voltages, whereas theinduction motor may be wound for comparatively low voltages. I haveselected for illustration a two-phase system, and

parts indicated by the same reference numerals as in Figs. 1 and 2,represent the same apparatus. It will be understood, however, that thetransforming devices may be introduced in systems of other phase and Jlvarious forms of connection. In series with the winding 11 of thesynchronous ma chine is connected the primary 21 of a transformer, thesecondary 22 thereof being connected in series with the winding 9 of theinduction motor. In series with the winding 12 across the two mains ofthe remaining phase is connected the primary winding 23 of thetransformer, the secondary 24 being connected in series with theinduction motor winding 10. A switch 25 is shown for short circuit-ingthe primary windings 21 and 23 after synchronism is attained and for thepurpose of rendering the transformer windings and induction'motorwindings inactive if desired. In starting with the apparatus of Fig. 5,practically'the full electromot-ive force of the supply mains will beapplied to the primary windings 21,23, and cause the secondary windings22, 24 to supply current to the induction motor for starting. Whensynchronism is attained the electromotive force applied to the primarywindings 21, 23 will not be appreciable on account of thecounter-elect-romotive force of the synchronous motor becomingeffective, and so causing substantially the full electromotive force tobe applied to the synchronous motor windings. The switch ,25 may then besafely closed if desired, as alreadyireferred to. I

I have illustrated the preceding forms with a View to explaining theapplication of my invention in var ous ways, and it will be understoodthat various other forms and arrangements of connections may be utilizedWithout departing from the scope of my invention, \Vhen transformers areintroduced they may be variously applied and grouped and connected inany of the well known ways, and apparatus of difl'erent phase maysometimes be combined in one system. Also, instead of providing, theinduction motor with a less number of than the synchronous machine, anyesirable means maybe utilized for obtaining the her of poles, or sets ofpoles, of the induction motor being less than the number of poles, orsets of poles, of the synchronous machine divided by the ratio of theangular l '1. The combination withza source of poly-- hase current of a)01 base s nchronous machine, a starting polyphase motor. means formechanically connecting the movable element of said motor to the movableelement of said machine to drive the same at a predetermined angularspeed. ratio. the number.

of poles of said motor being less than the' number of poles of saidmachine divided by the said speed ratio, and means for connecting thepolyphase windings of said machine respectively in series with thecorresponding polyphase windings of said motor between the terminals ofsaidsource.

2. The combination of a polyphase synchronous machine, a polyphaseinduction motor, means for mechanically connecting the movable elementof said motor to the movable element of said machine to drive the latterat a certain angular speed ratio, the number of poles of said inductionmotor be ing less than the number of poles of said synchronous machinedivided by the angular speed ratio, and means including a source ofpolyphase alternating current for energizing the polyphase windings ofsaid machine respectively in series with the corresponding polyphasewindings of said induction moto 3. The'combination, of a polyphasesynchronous machine connected thereto, a selfstarting polyphase motorhaving its movable oles desired speed relation, in each case thenumelement mechanically connected to the movof poles of said motor beingless than the sets of poles of said machine but greater than one half ofthe same, whereby said moto-r at or near its maximum speed causes saidsynchronous machine to be driven at a speed at which thecounter-electromotive force of the synchronous machine becomes efiectiveagainst the line voltage and the machine is automatically brought intosynchronism.

4. The combination of a source of alternating current, an alternatingsynchronous machine, an induction motor, means for me chanically drivingthe movable element of said machine by the movable element of said motorat a predetermined angular speed ratio, the number of poles of saidmotor being less than the number of poles of said synchronous machinedivided by the predeten, mined angular speed ratio, means including aswitch for connecting the winding of said motor in series with thewinding of said machine between the terminals of said source,

and a second switch for deenergizing the winding of said motor.

5. The combination of an alternating current synchronous machine andmeans for driving said synchronous machine up to synvoltage, said meanscomprising chronous speed and for automatically energizing the same atsubstantially full line nous alternating motor, and means for connectingthe Winding of said synchronous ma chine in series with the winding ofsaid motor.

6. The combination with an alternating current synchronous machinehaving a predetermined number of poles, of means for starting saidsynchronous machine from rest and for automatically causing the same tooperate under normal synchronous conditions, said means comprising aninduction motor, the movable element of which is mechanically connectedto the movable element of said machine to drive the same at a certainangular speed ratio, the number of poles L of said induction motor beingless than the number of poles of said synchronous machine divided by theangular speed ratio.

In testimony whereof I afiix my signature in presence of two witnesses.

JAMES BURKE. Witnesses: V A

L. K. SAGER, GEO. A. HOFFMAN.

an asynchro-

